no, there are only open source modifications of the closed source client.
Officially; No.
Informally; there's a few mods of the stock Discord client; however they're all closed source because they cannot possibly be fully open source as the stock Discord client is Closed Source.
Basically; alternatives exist; However they are not FOSS, FLOSS, OS or even fully Source Available.
Beeper exists but this is not strictly a Discord-only client and it is not fully Open Source; as some client/server code is only "Source Available". Beeper is also not fully "Free"; unless you self-host it. Furthermore access to Beeper is heavily join-gated. You will have to source an invitation code from someone you know. (No, I will not provide one.)
If you do get invited to Beeper; use Beeper Cloud, and be aware that iMessage integration does not work.
I've been with Beeper since beta testing and use it with Discord. iMessage works fine for me btw. If anyone wants an invite, then I'd be happy to give you one.
Just because it "Works For Me!" does not mean it will work.
Beeper very much does not currently allow new users to access the functioning legacy iMessage infrastructure; and Apple itself is making it impractical as well.
From the Beeper Community chatroom on Matrix:
[iMessage] Important Notice.
Beeper no longer provides support for iMessage-related issues.
It has become known that Apple has targeted users of legitimate Mac computers for using Beeper to generate iMessage registration data. Beeper has commented about this situation on Twitter/X here and coverage of this issue has been reported in the New York Times here.
As a result of this media pressure, many of those affected have been successful in having their hardware bans lifted. If you are still affected by a ban that you believe is related to generating a registration code on a Mac computer to use iMessage through Beeper please report it to Beeper Help here and please contact Apple Support as well.
As of this time Beeper has removed support for iMessage from Beeper Cloud due to Apple's actions. It is suggested that those still using registration data generated from a Mac computer to access iMessage through Beeper delete their existing iMessage bridge in Beeper Cloud.
For any further questions related to iMessage please visit our helpful Discord community.
I'd like one if you still have any
as foss as possible
I know this doesn’t answer your question, but using a 3rd party client or modifying the discord client is technically against the discord TOS. They don’t really enforce it unless you’re selfbotting or whatever, but there have been cases where people got banned from 3rd party clients because of a bug within the client that caused apparently bot-like behavior.
The only FOSS alternative is Matrix. Discord itself cannot/shouldn't be used with an alternative client because it's against the Discord TOS.
Aliucord
The app itself is outdated, it runs at v126 while we are now at v212
It still works though
"purple-discord" is the only free software Discord client I know about. It is a plugin for Pidgin and other libpurple based messengers such as Bitlbee.
"rdircd" the "reliable Discord client IRC daemon" might be an alternative but I've never used it.
Neither of these run out of the box on mobile but you can run them on a server you control, or maybe you could run them under Termux (have never tried this).
You can also use a Matrix or IRC bridge if you control the Discord "server."
I don't count client mods or web wrappers as they are fundamentally coupled to the proprietary client.
